There’s a really good youtube video series on katanas by I am Shad, talking about the pros and cons of katanas in a very well researched way. Summary: for pre-modern steel technology, they made a blade that was quite effective at slicing and cutting, at least among the best ever made; modern steel still kicks their a–, takes their lunch money, and makes them say they like wearing frilly dresses. There’s actually video of a katana being struck against a modern blade - the modern blade is fine, and the katana bends rather dramatically (it’s completely ruined).
That said, Musashi (the guy who wrote the Five Rings) really was, by all historical data, an amazing swordsman, who lived a full life and was never defeated in combat, so if you could somehow distill his combat ability (not just by reading the bloody book, which is available in any library), the results would certainly be amazing.[/quote]
From a guy who practices HEMA, the problem I see with Katanas and their martial art is mainly that they came from an isolated culture with no real means of developing increasingly better weapons and armour. Japan was isolated from the world for nearly all of their history, and as such their martial arts were only developed really from clever individuals who devoted their lives autistically to a mono-art. They had nobody else to learn from, or to test their swordsmanship on except for other people from the same culture. This caused them to stagnate, and for much of their history they used the same damn equipment with extremely few changes.
In Medieval Europe, all of the various countries had over a thousand years of constant war to perfect the art of killing humans with swords, and protecting humans with Armour. Many thousands of people were trained in the art of killing, and spent their whole lives perfecting it further and building upon the work of those before them. Every newly developed suit of plate armour was objectively superior to the last, but still owed its inspiration to its predecessor. If certain aspects of the Armour worked, they were put to great use in further suits, and parts that didn’t work out well were either phased out or improved upon until they finally did work.
The Zweihander and the Arming Sword both have over 1000 years of bugtesting, improvements, wars, and many thousands of nobles working on making them the perfect tool for killing. While the Katana is merely the work of an artisan who wanted to make a pretty sword. The katana doesn’t realistically stand up to other European weapons. It’s Fragile, takes too long to make, and was created using extremely low-grade materials due to a lack of battle-tested metalurgy. While the common Zweihander was made from superior metals tested over thousands of years of constant battle, and has been mastered in its construction to a point where an army can easily equip 50,000 people with one… TO USE AS THEIR SIDEARM.
